Elotuzumab in combination with thalidomide and low-dose dexamethasone: a phase 2 single-arm safety study in patients with relapsed/refractory multiple myeloma

Elotuzumab is an immunostimulatory, humanized immunoglobulin G1 monoclonal antibody that selectively targets and kills signalling lymphocytic activation molecule family member 7-expressing myeloma cells. We evaluated the safety and tolerability of elotuzumab 10mg/kg combined with thalidomide 50-200mg and dexamethasone 40mg (with/without cyclophosphamide 50mg) in patients with relapsed/refractory multiple myeloma (RRMM). The primary endpoint was the proportion of grade 3 non-haematological adverse events (AEs); other endpoints included the number of dose reductions/discontinuations and efficacy. Forty patients were treated, who had a median of three previous therapies, including bortezomib (98%) and lenalidomide (73%). Grade 3 non-haematological AEs were reported in 63% of patients, most commonly asthenia (35%) and peripheral oedema (25%). Six (15%) patients had an infusion reaction. Twenty-six (65%) patients had 1 dose reduction/discontinuation due to an AE, none related to elotuzumab. Overall response rate was 38%; median progression-free survival was 39months. Median overall survival was 163months and the 1-year survival rate was 63%. Minimal incremental toxicity was observed with addition of elotuzumab to thalidomide/dexamethasone with or without cyclophosphamide, and efficacy data suggest clinical benefit in a highly pre-treated population. Elotuzumab combined with thalidomide may provide an additional treatment option for patients with RRMM.